I. Field of the Invention
This invention relates generally to electrical stimulating apparatus and its manner of use in the treatment of physical ailments, and more specifically to a portable, self-contained pulse generator apparatus for producing bursts of stimulating pulses at desired rates and of progressively changing pulse widths, which when applied to a patient via body contacting surface electrodes, results in rhythmic contractions of selected muscle groups and either a rapid or a gentle relaxation of these muscle groups, thereby non-voluntarily exercising and strengthening them while simultaneously evoking a corrective movement of spinal vertebrae at a predetermined site or sites along the spinal column.
II. Discussion of the Prior Art
Heretofore, the most commonly employed treatment for mild-to-moderate scoliosis and other spinal deformities in children and adolescents has involved the use of body enclosing braces for maintaining the spinal column in a desired orientation by an orthosis as the skeletal system develops. This mode of treatment suffers a number of drawbacks. First of all, such a brace is non-cosmetic in appearance, restrictive in physical activities, and not particularly acceptable to psychologically sensitive adolescent patients because it tends to set them out as being different as far as their peers are concerned. Further, the treatment involving the use of a brace generally requires the patient to be confined therein for a twenty-three hour period each day and, unless it is carefully and properly fitted, it may lead to pressure sores and other irritations. Many patients are reluctant to wear the brace faithfully and, as a result, the spinal curvature may increase to a point where surgical correction (instrumentation and/or fusion) is necessitated.
A more recent and promising alternative to bracing involves the use of electrical muscle stimulation. In the Friedman et al U.S. Pat. No. 4,026,301 there is disclosed a system for electrical treatment of spinal curvature (scoliosis) in which an electronic stimulator is implanted in the body of a patient and a plurality of cork-screw type leads are positioned medially in the paraspinal musculature proximate the apex of the primary scoliotic curve. The pulse generator applies constant width impulses during successive "on" periods which are separated by an "off" period for the sole purpose of strengthening the muscles.
In the Wickman U.S. Pat. No. 3,983,881 there is also described an electronic stimulator circuit for applying electrical stimulating signals by way of body contacting surface electrodes to medial muscle groups on the concave side of a spinal curvature (scoliosis), the pattern of pulses being such as to periodically contract and relax these muscles in a rhythmic fashion, again to strengthen the selected muscles.
The apparatus and technique described in the Friedman et al Patent suffers from several serious drawbacks. First of all, with the implanted method, the lead wires used to couple the output from the pulse generator to the cork screw electrodes have not been able to withstand the millions of flexions to which they are exposed and, accordingly, the failure rate of the equipment employed has been high. Secondly, if the electrodes are not properly placed during the initial implant surgery, such that the appropriate muscles are stimulated, or if the electrode placement causes stimulation of an intercostal nerve bundle which creates inordinate pain, it becomes necessary to explant the device or, at least, to surgically relocate the electrodes. Another drawback of the treatment involving an implanted stimulator is that it necessarily results in explantation of the device upon treatment termination, and a disfiguring scar which may be objectionable to many patients.
The method and apparatus described in the aforereferenced Wickham Patent also has a number of significant drawbacks peculiar to it. While it overcomes some of the problems attendent in a surgically implanted approach, the Wickham method contemplates surface stimulation of midline or paraspinal musculature. Because of the limited experience using this approach, the results thereof are rather nonconclusive at the present time. However, it is believed that, to date, the use of the Wickham method has been limited to the treatment of lumbar curves only and that scolotic curvature in the thoracic region cannot be corrected or arrested using this technique because of the discomfort encountered due to excessive movement of the scapula. Then too, when surface stimulation of medial muscles is employed in an attempt to correct a primary curve, it has been found that the compensatory curve is oftentimes worsened. Also, when medial stimulation is employed, as in the Wickham and Friedman Patents, an increased extension of the spine (lordosis) is often noted. This could lead to increased permanent lordosis of the spine.
Furthermore, and as will be set out in greater detail hereinbelow, the prior art apparatus does not allow the degree of control over the stimulation pulse parameters as does the device of the present invention.